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AirHandling UNITS.ppt
- 1. Air Handling Systems Heating Ventilation and Air Conditioning (HVAC) Part 2: Components Supplementary Training Modules on GMP Module 3, Part 2: Components Slide 1 of 20 WHO - EDM
- 2. Module 3, Part 2: Components Slide 2 of 20 WHO - EDM Air Handling Systems Purpose of an air handling system Air Handling System Production Room With Defined Requirements Supply Air Outlet Air
- 3. Module 3, Part 2: Components Slide 3 of 20 WHO - EDM Air Handling Systems Objectives In the following slides, we will study the components of air handling systems in order to: 1. become familiar with the components 2. know their functions 3. become aware of possible problems
- 4. Module 3, Part 2: Components Slide 4 of 20 WHO - EDM Air Handling Systems + Production Room Exhaust air treatment Central air handling unit Terminal air treatment at production room level Fresh air treatment (make-up air) Main subsystems
- 5. Module 3, Part 2: Components Slide 5 of 20 WHO - EDM Air Handling Systems Filter Silencer Terminal filter Weather louvre Control damper Fan Flow rate controller Humidifier Heating coil Cooling coil with droplet separator Production Room Overview components + Prefilter Exhaust Air Grille Heater Secondary Filter Re-circulated air
- 6. Module 3, Part 2: Components Slide 6 of 20 WHO - EDM Air Handling Systems Weather louvre Silencer Flow rate controller Control damper To prevent insects, leaves, dirt and rain from entering To reduce noise caused by air circulation Automated adjustment of volume of air (night and day, pressure control) Fixed adjustment of volume of air Components (1)
- 7. Module 3, Part 2: Components Slide 7 of 20 WHO - EDM Air Handling Systems Heating unit Cooling unit /dehumidifier Humidifier Filters Ducts To heat the air to the proper temperature To cool the air to the required temperature or to remove moisture from the air To bring the air to the proper humidity, if too low To eliminate particles of pre-determined dimensions and/or micro-organisms To transport the air Components (2)
- 8. Module 3, Part 2: Components Slide 8 of 20 WHO - EDM Air Handling Systems Flow rate controller Control damper Humidifier Cooling battery Filters Ducts Blocked Poorly adjusted, bad pressure differential system Bad water/steam quality/poor drainage No elimination of condensed water/poor drainage Incorrect retention rate/damaged/badly installed Inappropriate material/internal insulator leaking Problems with components
- 9. Module 3, Part 2: Components Slide 9 of 20 WHO - EDM Air Handling Systems + Production Room Exhaust air Return air (re-circulated) Fresh air (make-up air) Supply air Air types
- 10. Module 3, Part 2: Components Slide 10 of 20 WHO - EDM Air Handling Systems Particles / m 3 0.5µm US 209D non- metric US 209E 1992 metric EC cGMP Annex I 1997 Germany VDI 2083 1990 UK BS 5295 1989 Japan JIS B 9920 1989 ISO 14644- 1 1 3,5 0 2 2 10 M 1 35 1 M 1.5 1 3 3 100 M 2 353 10 M 2.5 2 4 4 1.000 M 3 3.530 100 M 3.5 A, B A= unidirectional B= turbulent 3 E or F 5 5 10.000 M 4 35.300 1.000 M 4.5 4 G or H 6 6 100.000 M 5 353.000 10.000 M 5.5 C 5 J 7 7 1.000.000 M 6 3.530.000 100.000 M 6.5 D 6 K 8 8 10.000.000 M 7 Comparing International Cleanroom Classifications
- 11. Module 3, Part 2: Components Slide 11 of 20 WHO - EDM Air Handling Systems Filter classes Dust filters Standard Aerosol Fine Coarse ULPA HEPA 10 µ m > Dp > 1 µ m Dp > 10 µ m Dp < 1 µ m F5 - F9 G1 - G4 U 14- 17 H 11 - 13 EN 1822 Standard EN 779 Standard
- 12. Module 3, Part 2: Components Slide 12 of 20 WHO - EDM Air Handling Systems Average Efficiency Integral Value Peak Arrestance Local Value Retention in % Penetration Efficiency Penetration F9 85 0.15 H11 95 0.05 H12 99.5 5x10 -3 97.5 25x10 -3 H13 99.95 5x10 -4 99.75 25x10 -4 U14 99.995 5x10 -5 99.975 25x10 -5 Classification of filters according to their efficiency
- 13. Module 3, Part 2: Components Slide 13 of 20 WHO - EDM Air Handling Systems Primary panel filter Secondary filter HEPA or tertiaary filter
- 14. Module 3, Part 2: Components Slide 14 of 20 WHO - EDM Air Handling Systems Humidifier Silencer Heating and cooling units
- 15. Module 3, Part 2: Components Slide 15 of 20 WHO - EDM Air Handling Systems Control damper for air flow De-humidification Filter Pressure Gauges AHU with fan Variable Speed Controller Humid room air Air heater Regeneration air Humid room air Adsorber wheel Dry air Air handling unit
- 16. Module 3, Part 2: Components Slide 16 of 20 WHO - EDM Air Handling Systems Swirl Type air diffusors with terminal filters 1 Filter 2 Tightening frame 3 Register outlet 4 Screw fixation for register 1 2 3 4
- 17. Module 3, Part 2: Components Slide 17 of 20 WHO - EDM Air Handling Systems Low induction swirl diffusor (preferred) High induction office type diffusor (avoid)
- 18. Module 3, Part 2: Components Slide 18 of 20 WHO - EDM Air Handling Systems Annex 1, 17.26 Regulation of room pressure – pressure differentials concept Room pressure gauges Room pressure indication panel
- 19. Module 3, Part 2: Components Slide 19 of 20 WHO - EDM Air Handling Systems Pressure cascade injectables Protection from micro-organisms and particles Note : Direction of door opening relative to room pressure 15 Pa 0 Pa Air Lock 30 Pa Passage D C A B D LF Air Lock Air Lock 45 Pa Room 3 Room 2 Room 1 45 Pa 60 Pa 30 Pa Annex 1, 17.24, 17.25
- 20. Module 3, Part 2: Components Slide 20 of 20 WHO - EDM Air Handling Systems Pressure cascade solids Protection from cross-contamination Note : Direction of door opening relative to room pressure 15Pa 15Pa 15Pa E 30Pa Passage 0Pa Air Lock Room 3 Room 2 Room 1 15Pa Air Lock Air Lock
Editor's Notes
- In the first part of this module, we have examined the purpose of cleanroom classes, and how the air handling systems constitute the main factor in reaching the requirements of the hygiene classes. We now have to see how such systems are designed. However, in order to do this, we have to know what their components are, how they operate and what the risks associated with them are. The suggested time for Part 2 is 45 - 60 minutes. (Note for the trainer: the times noted are very approximate.)
- You will recognize this picture from a previous slide, but we repeat it in order to emphasize the following: An air handling system introduces pre-treated air, in order to provide a manufacturing environment with specified cleanliness, temperature and humidity in order to prevent product contamination and degradation. Air is then exhausted from the manufacturing environment.
- Objectives: For you, as inspectors, to be able to judge whether the air handling systems which you encounter during your factory inspections are adequate or not, it is necessary to know how such systems work, and to be aware of what problems may arise in terms of the components of the system. Therefore, the objectives of this part of module 3 are to study the components of air handling systems in order to: Become familiar with the components Know their functions Become aware of possible problems
- To understand the air handling systems, it is necessary to know what their components are. A conventional Air Handling System has 4 sub-systems: 1. Air handling of the incoming (fresh) air: elimination of coarse contaminants and protection from frost if necessary. In the case of air re-circulation, the fresh air is also called make-up air. 2. Central air handling unit (AHU), where the air will be conditioned (heated, cooled, humidified or de-humidified and filtered), and where fresh air and re-circulated air, if any, (indicated here by the dotted line) will be mixed. 3. Air handling in the rooms under consideration (pressure differential system, additional filtration, air distribution). 4. Air exhaust system (filtration).
- Another way to look at an air handling system is to consider the different components and to know their function. Some of the components, particularly the filters, are essential to ensure the quality of the air. We will later consider individual components in detail. Of course, a well-designed air handling system must not only be properly designed, but also properly installed, qualified and maintained (sealed ducts, tight filters). (The trainer should make the audience aware that this slide is just an example, and that all components may not necessarily be present in each system.)
- A typical HVAC unit consists of a small number of elements only. It is important that these elements are compatible, properly installed, and fulfilling their goal. Whereas a weather louvre and silencer are less critical elements, the components associated with the flow rate control are essential, as they allow adjustment of the air volumes supplied to the rooms, which in turn forms the base for a pressure differential concept: to have an automated or a fixed system is largely a financial matter, but a fixed system is more difficult to set up. Silencer – check internal lining material of silencer as this can cause contamination.
- Heating and cooling units (batteries), as well as humidifiers are used to adjust the climate in the room (temperature and humidity). Special de-humidifiers, on a dessiccant base, will be addressed later. Filters are one of the main components, as they determine the size of airborne particles that pass through them, and thus the hygiene class. It is wise to protect the finer filters by pre-filters, thus extending their life cycles, and making them less prone to clogging. Ducts transport the air from the air handling units to and from the rooms. Inspectors must verify that ducts do not have internal insulation as this is a great source of contamination.
- Problems may arise with components, with the following consequences: Flow rate controller Blocked No control of pressure differentials Control damper Poorly adjusted Bad pressure differential systems Humidifier Bad water/ Risks of microbial contamination steam quality Cooling Unit No elimination Risks of microbial contamination of condensed water Filters Incorrect retention Risks of contamination rate (particles, micro-organisms) Damaged Filter integrity fails Badly installed Risks of contamination (particles, micro-organisms) Ducts Inappropriate material Danger of corrosion Leaking duct work Intake of unfiltered air Internal insulation Inability to properly clean
- There are different air types to be considered within the air handling system: Fresh air (if the plant is of the re-circulation type, it is necessary to replace some of the re-circulating air with fresh air, which is then called make-up air). A proportion of about 15% fresh air is normal, but this proportion can vary, depending on factors such as number of people, National Regulatory Authority requirements, the presence of certain substances in the air, leakage due to pressure control, etc. Supply air to the rooms Exhaust air from the rooms Return air (about 85% is being re-circulated)
- There are different norms for the number of particles in the air. The table (refer to handout 3-2-10) shows that, for 0,5 micrometer particles, there are a number of names, those of the Federal Standard US 209 and the ISO guidelines being the most commonly in use at the moment. However, in the years to come, the ISO nomenclature will be generally adopted. The cleanroom classes for the pharmaceutical cleanrooms are highlighted in the table: We can see for instance that a Cleanroom class of type A corresponds to Non metric class 100 ( 100 particles / ft3 or 3.530 particles / m3) Metric class 3,5 ( logarithmic calculation ) ISO class 5
- The filtration efficacy depends on several mechanisms, and results in a rough filter classification. The diagram shows the commonly used classification, with current abbreviations G = Gross, F= Fine, H= High, U= Ultra. Filters are certified by the suppliers (challenge/efficiency test), but are often not properly installed or can be damaged. Leak tests (integrity tests), showing leakage of air through the filter itself or through its frame, therefore, have to be performed. Integrity tests are usually only carried out on the Aerosol filters (HEPA & ULPA). Integrity or penetration testing is performed to detect leaks from the filter media, filter frame and seal. The challenge is a poly-dispersed aerosol usually composed of particles ranging in size from one to three microns. The test is done in place and the filter face is scanned with a photometer probe; the measured downstream leakage is taken as a percentage of the upstream challenge. Integrity tests should be carried out with filters installed in the system and should be carried out by an independent body (not the filter supplier). The efficiency test, on the other hand, is used to determine the filter's rating. This test uses a mono-dispersed aerosol of 0.3 micron size particles, relates to filter media, and usually requires specialized equipment. Downstream readings represent an average over the entire filter surface. Therefore, leaks in a filter may not be detected by an efficiency test.
- This table gives an idea of the efficiency of the filters, calculated across the entire surface (integral value) or in particular spots (local value). Referring to filter ratings by percent efficiency is misleading, as there are so many different types of tests that give different efficiencies for the same filter. This can be very confusing and it is better to refer to the Committee of European Normalisation (EN) test rating i.e. G4, F8, H12, etc.
- This slide shows Primary Panel filters, which are used mainly for lower filtration efficiency or as pre-filters Secondary filters, consisting of mini-pleated media or filter bags, and is used for higher filtration efficiency. HEPA or tertiary filters, usually being the final filter in the system, providing the highest filtration efficiency. Though there is a strong relationship between filter efficiency and cleanroom class, a filter of a high efficiency does not guarantee a high cleanroom class, as many other elements play a role, such as Air flow (how the air is extracted, how well the room is “flushed”) Air speed and number of air changes Positions of air terminals Layout and presence of objects Personnel and clothing Equipment (not all machines are designed to operate in a clean environment!) Proper installation and proper maintenance
- This slide shows additional elements of the air handling units. For humidification purposes, especially in clean areas, high purity water should be used, to avoid contamination. The silencer is not important from a GMP point of view, but from an environmental one, as ventilation units can be very noisy. Be sure that the silencers are manufactured of suitable materials as the linings of standard silencers can contaminate air with particulates. Depending on the local legislation, the installation of silencers can be mandatory. The cooling unit is important during the hot season. Be aware that stagnating water (condensed water) can bring bacterial growth, which can contaminate the filters, pass through them (depending on their retention properties) and end up contaminating production areas. It is essential that there is no stagnating water. Cooling coils can be sanitized as well. Do remember that, if filters are not properly maintained, micro-organisms may grow through the filters and be carried towards the production rooms.
- Dampers to control pressure differentials are important. They can be automated or fixed. As filters get dirty the system pressure losses increase, and if airflow is not regulated, the flow decreases and pressure differentials change. This could cause flow reversal and cross-contamination. Variable speed drives for fan motors are also commonly used to control airflow. In some cases, it is necessary to have very dry air for galenical reasons in certain rooms (production of effervescent tablets and humidity sensitive products in general). To generate dry air, the air supplied to the production is passed over an adsorbant (silicagel, lithium chloride, etc.) where the humidity is removed from the air. The adsorbant is then re-generated, on a continuous or on a batch-wise base.
- The air flows into the rooms via so-called registers (diffusors), which are built and installed in such a way that the air is distributed evenly. Machinery or furniture can block the passage of air from the register to the exhaust point, creating unflushed zones, where counts of particles and micro-organisms could be higher. It is therefore important to consider the content of a clean room, when planning the HVAC system. In many cases, the terminal filter panel and diffusors are incorporated into one unit. It is also important that the air diffuser supplies air evenly and does not induce the circulation of dust in the room – as illustrated by the next slide.
- The diffuser on the left is a normal office type diffuser which induces a lot of air to rise vertically from the floor towards the ceiling. The rising induced air has the potential for carrying a lot of dust upwards which is then spread throughout the room with the air supply. This type of diffuser readily spreads contaminants in the room and should be avoided. The preferred type of diffuser for cleanroom applications is the swirl diffuser, or perforated plate diffuser. These types do not promote the spread of dust within the room.
- One of the main points in the design of production rooms is the pressure differentials concept. Pressure differentials must be defined, monitored and alarmed in critical cases. The overpressure of each room is measured against a reference point in the factory (point zero). As discussed earlier, the pressure regulation can be fixed or automated. Pressure control can be by means of automatic air flow control dampers (as shown in slide 15) or by means of fan speed control. Whatever the means used it is important to ask the manufacturer how they ensure that the pressure cascade is maintained as the filters get dirty. In the following slides, we are going to see that an overpressure concept can be very different for sterile products and for solid products.
- This slide illustrates the pressure differential system in a sterile area where the overpressure is kept high in the rooms, mainly in the A/B class room, to prevent the entry of micro-organisms. (The level of overpressure is reflected by the absolute pressure in Pascals). To enter all rooms, it is necessary to go through airlocks. In this particular example, the pressure differential in sterile areas is set up at 15 Pa between zones of different cleanliness, in accordance with FDA, EC and PIC/S regulations. Other values may apply in other regions. It must be understood that high pressure differentials have an influence on the stability of building elements such as walls and doors. Factory layouts must be carefully planned, in order not to have too high a pressure differential between entrance and exit of a sterilising or depyrogenating tunnel, as the air flow may significantly affect the temperature in a tunnel. Pressure differentials must be constantly monitored. The loss of overpressure in a filling room for injectables may mean the loss of the batches under production and the need for complete sanitation of the facility. It is therefore essential that the systems are designed in such a way that there is no loss of overpressure in case of power loss (overpressure fan should be linked to emergency power grid).
- This slide illustrates the pressure differential system in a solids area where the overpressure is kept high in the corridors, to prevent cross-contamination. In this case, we are not too worried by the microbial contamination, but rather by dust coming out of rooms where process work is being done, and thus contaminating other rooms. The entry into some rooms (containing dangerous products such as hormones, cytotoxics, low RH products or strongly coloured products) is protected by airlocks.